feat: add Записаться button to group cards with pre-filled Instagram DM

- BookingModal now accepts optional groupInfo for pre-filled message
- Trainer profile: each group card has Записаться button
- Schedule group view: each group card has Записаться button
- Message includes class type, trainer, days, and time

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/sections/schedule/GroupView.tsx

@@ -55,6 +55,7 @@ interface GroupViewProps {
   filterTrainer: string | null;
   setFilterTrainer: (trainer: string | null) => void;
   showLocation?: boolean;
+  onBook?: (groupInfo: string) => void;
 }
 
 export function GroupView({
@@ -65,6 +66,7 @@ export function GroupView({
   filterTrainer,
   setFilterTrainer,
   showLocation,
+  onBook,
 }: GroupViewProps) {
   const groups = buildGroups(filteredDays);
 
@@ -177,6 +179,14 @@ export function GroupView({
                   </div>
                 ))}
               </div>
+              {onBook && (
+                <button
+                  onClick={() => onBook(`${group.type}, ${group.trainer}, ${group.slots.map(s => s.dayShort).join("/")} ${group.slots[0]?.time ?? ""}`)}
+                  className="w-full mt-3 rounded-xl bg-gold/15 border border-gold/25 py-2 text-xs font-semibold text-gold-dark dark:text-gold hover:bg-gold/25 transition-colors cursor-pointer"
+                >
+                  Записаться
+                </button>
+              )}
             </div>
           </div>
         );